This invention relates to methods of forming dielectric layers and to methods of forming capacitors.
Dielectric material layers are essential components in integrated circuitry capacitors, and are typically interposed between two capacitor plates. Capacitors are used in memory circuits, such as dynamic random access memory (DRAM) arrays.
As device dimensions continue to shrink, an important emphasis is placed on maintaining, and in some instances, increasing a capacitor""s ability to store a desirable charge. For example, a capacitor""s charge storage capability can be increased by making the capacitor dielectric thinner, by using an insulator with a larger dielectric constant, or by increasing the area of the capacitor. Increasing the area of a capacitor is undesirable because the industry emphasis is on reducing overall device dimensions. On the other hand, providing a thinner capacitor dielectric layer and/or using an insulator with a larger dielectric constant can present problems associated with current leakage, such as that which can be caused by Fowler-Nordheim Tunneling. Current leakage can significantly adversely impact the ability of a capacitor to store a charge.
This invention grew out of needs associated with providing methods of forming dielectric layers having sufficiently high dielectric constants. This invention also grew out of needs associated with providing methods of forming capacitor constructions which have desirable charge storage characteristics, and reduced current leakage.
Methods of forming dielectric layers and methods of forming capacitors are described. In one embodiment, a substrate is placed within a chemical vapor deposition reactor. In the presence of activated fluorine, a dielectric layer is chemical vapor deposited over the substrate and comprises fluorine from the activated fluorine. In another embodiment, a fluorine-comprising material is formed over at least a portion of an internal surface of the reactor. Subsequently, a dielectric layer is chemical vapor deposited over the substrate. During deposition, at least some of the fluorine-comprising material is dislodged from the surface portion and incorporated in the dielectric layer. In another embodiment, the internal surface of the reactor is treated with a gas plasma generated from a source gas comprising fluorine, sufficient to leave some residual fluorine thereover. Subsequently, a substrate is exposed within the reactor to chemical vapor deposition conditions which are effective to form a dielectric layer thereover comprising fluorine from the residual fluorine.